As the name suggests, people with relapsing-remitting MS have flare-ups when new symptoms appear or olds ones return or worsen. There are also periods of remission with partial or full recovery.

"In clinical trial situations, it has been quite evident for years that patients receiving beta interferon treatment have reduced frequency of relapses as well as reduced frequency of new lesions seen on MRI," Dr. Joel Oger, who is also a neurologist with the UBC Hospital MS Clinic, said in a release.

"This study following a large number of patients for a long time in 'real life situation' does not show an association of the beta interferons with long term disability and tends to confirm a more modern way of understanding MS: relapses may not be responsible for long term disability in all patients and another mechanism might be at work as well."

The study in Wednesday's issue of the Journal of the American Medical Association compared 868 people prescribed the drug with 829 who were untreated as well as 959 who were treated before interferon beta was approved.

"The ultimate goal of treatment for MS is to prevent or delay long-term disability," the study's authors concluded.

"Our findings bring into question the routine use of interferon beta drugs to achieve this goal in MS."

Making 'the right choices'

Instead, the results encourage the investigation of new treatments and ways of identifying which patients might benefit from interferon beta, the researchers said.

Despite the findings, it is likely that neurologists will keep prescribing interferon beta and other interferons and that people with relapsing-remitting MS will continue the injections, based on data on the short-term benefits, particularly for people in the early phase of the disease, Dr. Tobias Derfuss and Dr. Ludwig Kappos of University Hospital Basel in Switzerland said in a journal editorial accompanying the research.

"The relatively low progression rate in the untreated contemporary cohort is reassuring because it indicates that despite the unreliable explicit prognostic criteria, neurologists and patients in British Columbia seem to have made the right choices."